It may not tell us much that's new, but there's something exhilarating about this thoroughly enjoyable and worthwhile docu-blast against Tony Blair's insidious diminution of native British liberties. Director Chris Atkins shows how, since 1997, New Labour's residual passion for ideology, combined with a fear of looking Spartist or soft on terror, has combined to deliver a panic-stricken abandonment of liberties that we'd somehow held on to in the face of Nazi Germany and the IRA.

Some pundits may find it deficient in sophistication or the fence-sitting neutrality of good taste; for me it was a vitamin-boost of scepticism. Cheerful, polemical and tactless, Atkins's film raises a celebratory glass to the spirit of British awkwardness and bloody-mindedness, the dissident spirit that infuses both the anti-war protesters and the Countryside Alliance - Mark Thomas and Boris Johnson alike. "What about Magna Carta?" demands Tony Hancock in a nicely chosen clip. "Did she die in vain?" In the strangest way, Hancock is the tutelary deity behind many of the English protesters here: very often elderly and apolitical souls who feel they have earned the right not to be bullied by the macho-menopausal apparatchiks of the Blair/Brown succession.

It is an old story. Mr Blair was once ferociously against ID cards, and now he loves them. He once regaled audiences with anecdotes, combined with bittersweet shrugs, to the effect that protesters yelled nasty things at him as he was driven into Westminster in his official car, but gosh, how wonderful to live in a country where folk are free to shout nasty things. Now he feels he can and will live without these protesters. He is an enthusiast for increasing detention without charge, for the vast internment camp at Guantánamo Bay. And this trained barrister is not straining his forensic and analytic abilities to investigate the mounting circumstantial evidence that extraordinary rendition flights are stopping off at Manchester and Prestwick.

September 11 was the key event - and yet the Anglo-American crackdown on radical Islamic terrorism is, in the oddest way, not the most powerful moment in the movie. That honour goes to the case of the NatWest Three: three British bankers accused of white-collar fraud by the American authorities and extradited there with no evidence presented to the British CPS. Our submission to US rule on 9/11 issues simply encouraged America to believe that its writ extends beyond its borders on any and every other issue.

Atkins captures pungent moments of low comedy. A police-protected bailiff is captured thrusting court orders at protesters with a jolly cry of "Served!" Later, a protester is shown trying to turn the tables, stuffing a revised court order into the hands of a policeman who is humiliated and angered beyond any rational measure by this casting-the-runes manoeuvre. He insists the man take the document back and threatens to nick him for littering.

It all makes for a shabby and abject story, a paradoxical tale of weakness from a political generation from which 10 years ago we expected such strength and self-belief. They are still in deep denial; we are waking up.